1. Field of the Invention
The present invention relates to an apparatus and a method for transferring works, such as chip-type electronic components, from one transportation table to another transportation table and transporting them while carrying out various processes, such as measurement of their electrical properties, sorting, etc., and more particularly, to a work transferring and transporting apparatus and a work transferring and transporting method, capable of coping with the trend toward higher-speed transportation between a plurality of transportation tables and suited for inspection of the external appearance of works.
2. Description of the Related Art
An apparatus for transferring and transporting chip-type electronic components or the like is described in Jpn. Pat. Appln. KOKAI Publication No. 10-74673, for example. This prior art apparatus is constructed in the manner shown in FIG. 5. This work transferring and transporting apparatus 20 comprises a first transportation table 21 and a second transportation table 22 having axes of rotation that extend at right angles to each other. A plurality of work storage recesses 23 and 24 are formed in the respective outer peripheral edge portions of the transportation tables 21 and 22 so as to be arranged at regular pitches in the circumferential direction.
Divided work supply means 25 is located near the first transportation table 21. Works W that are supplied from the supply means 25 are trapped one after another into the work storage recesses 23 of the first transportation table 21 that rotates intermittently. The works W are subjected to external inspection or measurement of electrical properties in a first processor 26 as they are transported by means of the intermittently rotating table 21. Those works W which are then concluded to be defective or nonstandard are discharged in the first processor 26.
Those works which are concluded to be nondefective in the first processor 26 are transferred to the work storage recess 24 of the second transportation table 22 by means of a work transferring means 27. The first and second transportation tables 21 and 22 intermittently rotate in a separate manner and temporarily stop with their respective work storage recesses 23 and 24 opposed to each other. The works W undergo inspection and the like in a second processor 28 as they are transported by means of the second transportation table 22 that rotates intermittently.
External inspection of the surfaces of the works W that is complementary to the inspection in the first processor 26 is carried out in the second processor 28. Those works W which are checked for defectiveness in the second processor 28 are transported to a discharge section 29 by means of the second transportation table 22. Those works which are concluded to be nondefective are transported to the next stage, while those ones which are concluded to be defective or nonstandard are discharged in the discharge section 29.
In the transferring and transporting apparatus 20 constructed in this manner, the transportation tables 21 and 22 are intermittently rotated to transport the works W in the aforesaid manner. In some cases, therefore, trouble may be caused by vibration as the transportation tables 21 and 22 rotate intermittently. Further, the works W may fail to be properly transferred, owing to jamming in work transfer means 27, or the apparatus cannot cope with the trend toward higher-speed processing, due to the limited transfer speed of the work transfer means 27 or the limited rotational speed for the intermittent rotation.
In order to solve this problem of the intermittent rotation, therefore, a chip component transferring apparatus that continuously rotates transportation tables is described in Jpn. Pat. Appln. KOKAI Publication No. 11-268824. This prior art apparatus is constructed in the manner shown in FIGS. 6 and 7. FIG. 6 is a plan view of the transferring apparatus. In this transferring apparatus, a feeding disc 30 and a transporting disc 32 are arranged side by side. Cavities 31 are formed in the feeding disc 30. The peripheral edge portion of the transporting disc 32 is formed having cavities 33, which store the chip components and other works W.
The works W such as chip parts are transferred individually to the cavities 31 of the feeding disc 30. They are transported as the feeding disc 30 rotate and are transferred individually to the cavities 33 of the transporting disc 32 that adjoins the feeding disc 30. Then, the works W are transported again as the transporting disc 32 rotates and are transferred individually to cavities 36 of a carrier tape 35.
FIGS. 7A, 7B and 7C sequentially show the way a work W is transferred from the feeding disc 30 of FIG. 6 to the transporting disc 32. As shown in FIG. 7A, the work W is held in one of the cavities 31 in the outer periphery of the feeding disc 30 by air suction. The work W projects from the outer periphery of the feeding disc 30. Air suction of the feeding disc 30 is stopped when the work W is opposed to one of the cavities 33 of the transporting disc 32. At the same time, the work W is transferred to the transporting disc 32 when the cavity 33 of the transporting disc 32 is subjected to air suction.
According to this prior art, the discs 30 and 32 continuously rotate in synchronism with each other so that the cavities 31 of the feeding disc 30 successively face the cavities 33 of the transporting disc 32. However, this prior art has the following problems.
(1) The feeding disc 30 and the transporting disc 32 require high-accuracy synchronous rotation. If the synchronous rotation is subject to the slightest deviation, the works W that project from the cavities 31 may run against the outer periphery of the transporting disc 32 and break. For example, dust may collect between the cavities 31 and 33 and the works W or the air suction may fail to be switched properly, so that the works W cannot be transferred smoothly, in some cases.
As shown in FIG. 7B, for example, the works W sometimes may stop at a position intermediate between the feeding disc 30 and the transporting disc 32. If the discs 30 and 32 continue to rotate in the directions of the arrows in FIG. 7B in this state, the works W are subjected to a bending force between the cavities 31 and 33. In this case, the works W or the cavities 31 and 33 may possibly be broken.
(2) If the gaps between the cavities 31 and 33 and the works W are enlarged to solve the problem described in item (1), the works W cannot be transferred steadily. Thus, the air suction of the transporting disc 32 suffers an increased leakage, so that the sucking force for the works W lowers.
(3) The property measurement or external inspection for the works W is carried out as the works W are transported. If the gaps between the works W and the cavities 31 and 33 are too wide, the positions of the works W change, so that the measurement or inspection is liable to failure.
(4) Since the works W are transferred between the discs 30 and 32 while the feeding disc 30 and the transporting disc 32 are rotating continuously, it is hard to use a sensor. Since the discs 30 and 32 rotate continuously, moreover, they cannot be easily stopped in a moment in case of trouble. On the other hand, the transportation tables 21 and 22 shown in FIG. 5 rotate intermittently. Therefore, trouble in the works W can be detected by means of a sensor, or the tables 21 and 22 can be stopped in a moment.
According to the conventional intermittent rotation system (FIG. 5), as described above, the processing speed is low, although the operation is highly reliable. On the other hand, the continuous rotation system (FIGS. 6 and 7) lacks in reliability, although it enjoys a high processing speed.